In order to assess the environmental risks of a compound it is imperative to have suitable and reliable techniques for its determination in environmental matrices. In this paper, we focused on a method development for the recently introduced online coupling of a field flow fractionation (FFF) system to an Orbitrap-HRMS, that allows the simultaneous size and concentration determination of different aqueous fullerene aggregates and their concentrations in different size fractions. A 0.05% NH4OH solution in water was identified as the best carrier liquid for the analysis of the three different aqueous fullerene suspensions (C60 [60], [6,6]-phenyl-C61 butyric acid methyl ester ([60]PCBM) and [6,6]-(bis)phenyl-C61 butyric acid methyl ester ([60]bisPCBM)). The multi-angle light scattering (MALS) data received after employing the ammonia solution was consistent with both the theory and calibration using well defined Au and latex particles. The LODs obtained using Orbitrap HRMS detection were 0.1 μg L−1 for an injection volume of 100 μL which are significantly better than the LODs obtained by using UV (20 μg L−1) and MALS detectors (5 μg L−1). However, these LODs can be further improved as in theory there is no limit to the amount of sample that can be injected into the FFF. Environmental samples (river and sewage water) were spiked with fullerenes and the fractograms obtained for these samples revealed that the matrix does affect the size of fullerene aggregates. Information on the size distribution can be useful for the risk assessment of these particles. 相似文献
High‐temperature chlorination of fullerene C88 (isomer 33) with VCl4 gives rise to skeletal transformations affording several nonclassical (NC) fullerene chlorides, C86(NC1)Cl24/26 and C84(NC2)Cl26, with one and two heptagons, respectively, in the carbon cages. The branched skeletal transformation including C2 losses as well as a Stone–Wales rearrangement has been comprehensively characterized by the structure determination of two intermediates and three final chlorination products. Quantum‐chemical calculations demonstrate that the average energy of the C?Cl bond is significantly increased in chlorides of nonclassical fullerenes with a large number of chlorinated sites of pentagon–pentagon adjacency. 相似文献
A facile and efficient methodology for the formation of polymer‐fullerene networks via a light‐induced reaction is reported. The photochemical crosslinking is based on a nitrile imine‐mediated tetrazole‐ene cycloaddition reaction, which proceeds catalyst‐free under UV‐light irradiation (λmax = 320 nm) at ambient temperature. A tetrazole‐functionalized polymer (Mn = 6500 g mol−1, Ð = 1.3) and fullerene C60 are employed for the formation of the hybrid networks. The tetrazole‐functionalized polymer as well as the fullerene‐containing networks are carefully characterized by NMR spectrometry, size exclusion chromatography, infrared spectroscopy, and elemental analysis. Furthermore, thermal analysis of the fullerene networks and their precursors is carried out. The current contribution thus induces an efficient platform technology for fullerene‐based network formation.
The thermal reaction of the endohedral metallofullerene La2@D2(10611)‐C72, which contains two pentalene units at opposite ends of the cage, with 5,6‐diphenyl‐3‐(2‐pyridyl)‐1,2,4‐triazine proceeded selectively to afford only two bisfulleroid isomers. The molecular structure of one isomer was determined using single‐crystal X‐ray crystallography. The results suggest that the [4+2] cycloaddition was initiated in a highly regioselective manner at the C? C bond connecting two pentagon rings of C72. Subsequent intramolecular electrocyclization followed by cycloreversion resulted in the formation of an open‐cage derivative having three seven‐membered ring orifices on the cage and a significantly elongated cage geometry. The reduction potentials of the open‐cage derivatives were similar to those of La2@D2‐C72 whereas the oxidation potentials were shifted more negative than those of La2@D2‐C72. These results point out that further oxidation could occur easily in the derivatives. 相似文献
A two‐step synthesis of a strained π bowl, with hemifullerene skeleton from sumanene, was achieved in a high yield. The first step is a base‐promoted condensation reaction with a benzophenone compound, bis(3,5‐dimethylphenyl)methanone. The second step is the regioselective intramolecular oxidative cyclization, which is a key reaction for the hemifullerene skeleton synthesis. This regioselective cyclization is likely to be under thermodynamic control. This strategy will allow facile synthesis of various highly strained π bowls. 相似文献
An open‐cage C60 tetraketone with a large opening was able to encapsulate N2 and CO2 molecules after its exposure to high pressures of N2 and CO2 gas. A subsequent selective reduction of one of the four carbonyl groups on the rim of the opening induced a contraction of the opening (→ 2 ) and trapped the guest molecules inside 2 . The thus‐obtained host–guest complexes N2@ 2 and CO2@ 2 could be isolated by recycling HPLC, and were found to be stable at room temperature. The molecular structures of N2@ 2 and CO2@ 2 were determined by single‐crystal X‐ray diffraction analyses, and revealed a short N?N triple bond for the encapsulated N2, as well as an unsymmetric molecular structure for the encapsulated molecule of CO2. The IR spectrum of CO2@ 2 suggested that the rotation of the encapsulated molecule of CO2 is partially restricted, which was supported by DFT calculations. 相似文献
Peripherally hexachlorinated meso‐triphenyl subporphyrin 4 was prepared by chlorination of meso‐triphenyl subporphyrin 1 with N‐chlorosuccinimide and was effectively transformed to hexasulfanylated subporphyrins 5 – 8 via nucleophilic aromatic substitution (SNAr) reactions with the corresponding thiols under basic conditions. The structures of 5 – 8 have been all well characterized by single‐crystal X‐ray analysis. 1H NMR studies indicated that the meso‐phenyl substituents undergo restricted rotation for 5 – 8 , while the β‐sulfanyl substituents are conformationally flexible in 5 , 6 , and 8 , and are strictly regulated to an anti‐conformation in 7 . Judging from the absorption spectra, the oxidation and reduction potentials, and the DFT calculations, the substituent effects decrease in the order of 5 > 6 > 7 > 8 . Subporphyrin 8 effectively captures C60 in a 1:1 manner in [D8]toluene solution. 相似文献
The energetics and photodynamics of carbonaceous molecular bearings with discrete molecular structures were investigated. A series of supramolecular bearings comprising belt‐persistent tubular cycloarylene and fullerene molecules accepted photonic stimuli to afford charge‐separated species via a photoinduced electron transfer process. The energy conversion processes associated with the photoexcitation, however, differed depending on the molecular structure. A π‐lengthened tubular molecule allowed for the emergence of an intermediary triplet excited state at the bearing, which should lead to an energy conversion to thermal energy. On the other hand, low‐lying charge‐separated species induced by an endohedral lithium ion in fullerene enabled back electron transfer processes to occur without involving triplet excited species. The structure–photodynamics relationship was analyzed in terms of the Marcus theory to reveal a large electronic coupling in this dynamic supramolecular system. 相似文献